1. Field of the Invention
Although paints exist which dry rapidly underwater, underwater painting has not, up to now, been practiced over large surfaces, using rapid implementation methods.
Different apparatus for applying paint to an immersed surface, using moving brushes, have been described in particular in patents FR-A-1 567 045, FR-A-2 342 875, FR-A-2 389 420, FR-A-2 462 201, FR-A-2 144 115, FR-A-2 195 925, FR-A-2 369 952, U.S. Pat. Nos. 2,806,236, 4,084,535, 4,058,082 and 3,303,812.
All these apparatus are either complex in construction or delicate to adjust or insufficiently reliable in operation.
The invention relates more particularly to apparatus which comprise at least one moving application brush in which the active end of the bristles comes into contact with the surface to be painted substantially perpendicularly thereto and comprises a permanent paint supply device.
The apparatus is moved in translation over this surface to be painted, the most often by a diver. The two essential problems to be solved in the construction of this kind of apparatus are the regular paint supply so as to obtain an adherent coat and to avoid losses of paint in the water and the formation of solid deposits on the bristles, and equalization of the coat by smoothing
Equalization may be obtained either by scrapers made from a resilient material (FR-A-1 567 045), or by means of rotary smoothing brushes (FR-A-2 462 201). The application brush is either driven in movement about its axis (FR-A-2 342 875), or subjected to a reciprocating translational movement, which may be parallel to the surface to be painted (FR-A-1 567 045) or perpendicular thereto (FR-A-2 389 420), this perpendicular translation being possibly accompanied by a rotary movement (FR-A-2 389 420).
The supply is provided either at the periphery of the application brush (FR-A-1 567 045), or at the center thereof (FR-A-2 342 875).
2. Description of the Prior Art
According to patent FR-A-2 565 508, the bristles are supplied at the center of tufts of bristles which form the application brush at points situated at the non active ends of said tufts. The paint is distributed radially from a central channel into the tuft of bristles, forming a hole in the support of the tuft and arrives along the bristles as far as the application end. This solution functions correctly, provided that the injection pressure of the paint is adjusted with great accuracy, on the one hand, and that the pulsating movement perpendicular to the surface to be painted to which the bristles are subjected is adjusted to correctly drive out the water between the surface and the application end of the bristles (stencil effect), on the other; it is important that there is no breakage of the paint film during the application, which requires very delicate adjustments. Such adjustments depend more particularly on the rotational speeds of the brushes of the apparatus moving in translation over the surface and the thickness of the desired coat.
The U.S. Pat. No. 3,860,987 describes an underwater painting device comprising a brush rotating about an axis substantially perpendicular to the surface to be painted, characterized in that the brush has at least two separate zones in which the bristles have different hardnesses, the zone of the more flexible flexible bristles which serves for smoothing, surrounding the zone of harder bristles, which serves for depositing the paint. The free ends of the supple bristles extend beyond the free ends of the harder bristles and the paint is supplied by means of flexible duct portions which pass between the bristles of the harder bristle zone and whose ends emerge in the vicinity of the free end of the bristles. In this arrangement, only the central zone of the brush participates in the paint supply and, in addition, since the bristles of the outer zone are longer than those of the central zone, the flexible tubes do not emerge in the immediate vicinity of the surface to be painted.